It is known from SE 451 791 to produce milk products with extended shelf life. According to this patent, the milk is divided into two fractions in a centrifugal separator. The skimmed milk fraction is led to a microfilter and divided into a permeate flow of low bacterial content and a concentrate flow which contains minute cream globules and bacteria. The concentrate flow is sterilized and remixed with the permeate flow in order to give a milk product with a predetermined fat content. In order to achieve the desired bacteria separation, microfilters of a pore size of 0.2-1.0 .mu.m are employed.
U.S. Pat. No. 5,256,437 describes a method of producing milk with a bacteria content which is lower than in the raw milk. According to this patent specification, the milk is homogenized and, within five minutes of this treatment, the milk undergoes a dynamic microfiltration process.